In a standard power-lock system, which is invariably centrally controllable, it is becoming standard to set up the individual door latches so that they have, in addition to the standard locked and unlocked positions, an antitheft position. While in the locked position it is still possible for a person to unlock and then open a door from inside the vehicle, typically by first actuating the inside locking button or lever to unlock the door, in the antitheft position the door cannot be opened even from inside. Thus the inside locking element is disconnected from the respective latch mechanism or is blocked against movement. Thus a person who, for example, breaks the vehicle window, cannot simply reach inside and unlock the door. A drive for such a system having a slider as the actuating element is described in commonly owned earlier U.S. Pat. No. 4,669,283.
In another known system described in German utility model 9,012,785 filed 7 Sep. 1990 (with a priority claim to German 8,910,972 filed 14 Sep. 1989) uses a rotary actuating element that is moved between two angularly offset positions between the locked and unlocked positions, and that is retained in the locked position in the antitheft position. Such a system has some advantages over other prior-art arrangements but is still fairly complex.